The fabrication of semiconductor devices, such as logic and memory devices, typically includes processing a substrate such as a semiconductor wafer using a large number of semiconductor fabrication processes to form various features and multiple levels of the semiconductor devices. As semiconductor device size becomes smaller and smaller, it becomes critical to develop enhanced inspection and review devices and procedures.
One such inspection technology includes electron beam based inspection systems, such as, scanning electron microscopy (SEM). In one mode, SEM systems may image a surface of a sample through the collection and analysis of secondary electrons emitted from the surface of the sample as a primary beam is scanned across the sample. Typical SEM systems include a Wien filter located within the electron-optical column of the SEM and positioned above the sample for the purposes of deflecting the secondary electrons to a secondary electron detector.
The utilization of the Wien filter for splitting secondary electrons from the primary beam may cause chromatic aberration in the primary beam. Therefore, it would be advantageous to provide a system and method that provides correction for chromatic aberration in the primary beam and cures the shortcomings of the previous approaches identified above.